Adjustable fuel injection pump



Dec. 31', 1963 c. KOESTER 3,115,838

ADJUSTABLE FUEL INJECTION PUMP Filed Nov. 15, 1962 United States Patent O 3,115,833 ADIUSTABLE FUEL INIECTEN PUMP Claus Koester, Backnang, Germany, asslgnor to Robert Bosch G.m.bH., Stuttgart, Germany Filed Nov. 13, 1962, Ser. No. 236,392. Claims priority, application Germany Nov. l1, 1961 8 Claims. (Cl. 163-2) The present invention relates to fuel injection pumps.

Fuel injection pumps are well known for the purpose of controlling the delivery of fuel to the cylinders of an internal combustion engine. A particular problem resides in the manner in which such fuel injection pumps are regulated .for the purpose of adjusting the amount of tucl which is delivered to the internal combustion engine.

It is an object of the present invention to provide for a fuel injection pump a relatively simple structure which is capable of precisely regulating the amount of fuel which is delivered to the internal combustion engine.

Another object of the present invention is to provide a structure of this type which 4has no particular problem with respect to the sealing of the movable elements which are moved during adjustment of the amount of fuel delivered to the engine.

Still another object of the present invention is to provide a structure wherein a piston which participates in the adjustment of the a-mount of fuel delivered to the engine is capable of being guided without any interruptions so that the guidi-ng of this piston is very precise.

An additional object of the present invention is to provide a structure of the above type where the adjustable elements which regulate the amount of fuel delivered to the engine have with respect to each other no undesirable frictional relationship during the operation of the pump.

With these objects in view the invention includes, in a fuel injection pump, a pump chamber means land a pump piston means movable, during operation of the injection pump, along pressure and suction strokes in the pump chamber means. The pump of the invention also includes a yieldable piston means as well as a lmeans which places the yieldable piston means in communication with the pump chamber means so that the yieldable piston means will move away from the pump chamber means during the pressure stroke-s of the pump piston means. A cylindrical body receives, slidably, a portion -o-f the yieldable piston means so that the latter moves further into the cylindrical body during the pressure strokes of the pump piston means, and the cylindrical body is formed with an aperture through which fuel discharges from the inter-ior of the oylindrical body during movement oi the yieldable piston means `further into the cylindrical body. A conduit means communicates with the pump chamber means for directing fuel therefrom to the engine only when the aperture of the cylindrical body has been closed by the yieldable piston means, and with the structure of the invention an adjusting means is operatively connected to the cylindrical body for adjusting the latter axially so as to regulate the distance through which the yieldable piston means moves Ibefore `closing the aperture of the cylindrical body, so that in this way the amount of fuel delivered to the engine during the pressure strokes of the pump piston means can be adjusted.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its additional objects and advantages thereof, will be best understood from the following description of specie embodiments when read in connection with the accompany-ing drawing in which there is shown in an axial, sectional, elevational view an injection pump constructed 3d ld Patented Dec. 31, 1963 "ice 2 according to the present invention, part of the structure being shown diagrammatically.

Referring to the drawing, the injection pump illustrated therein is adapted to suply fuel to a multi-cylinder internal combustion engine, and the injection pump has a housing made up of the elements l and 2 which are fixed to each other. The housing part 1 supports for rotary movement a drive means in the form of a rotary drive shaft 3 supported for rotation about its axis and driven from the engine itself in a manner well known in the art. The rotary drive shaft or drive means 3 has an enlarged portion i which rotates Within the housing l, 2 and the portion 4 is formed with a bore which extends perpendicularly across the axis o-f the shaft 3 to form a pair of pump cylinders which are coaxial and extend radially with respect to the axis of the shaft 3, and a pair of pump pistons 5 are axially reciprocable in the pair of cylinders formed in the portion 4- of the rotary drive shaft 3. At their outer ends the pistons `5 are touching a pair of members 6 formed with bearings Ifor rollers 7 which respectively ride along a cam surface il formed at the inner periphery of a cam ring 9 which is fixedly carried by the housing portion l be-tween the latter and the housing portion 2, so that during rotation of the shaft 3 the rollers 7 will ride along the cam surface and move toward and away from each other so that the pistons 5, which form the pump piston means, will reciprocate toward `and away from each other along their pressure and suction strokes, respectively. As is well known in the art, the number of camming projections of the surface 3 corresponds to the number of cylinders in the internal comb-ustion engine to provide during each revolution of the shaft 3 reciprocations of the pistons 5 toward and away lfrom each other a number of times which will deliver to the several cylinders of the :internal combustion engine the required fuel for driving the engine. The bore which forms the cylinders receiving the pistons 5' provides between the pistons 5 the pump chamber means lll into which the yfuel flows during the suction strokes of the pump piston means 5 and out of which the fuel flows during the pressure strokes of the pump piston means 5.

A distributor means in the form of -a disc 1l is located over the portion i of the shaft 3, and the distributor means ll has a downwardly directed, central portion l2 which extends slidably and fluid-tightly into an axial bore of the shaft 3 formed at the upper portion of the part 4l thereof 4and communicating with the pump chamber iti. A pin 13 extends into bores of the portion 4 of the shaft 3 and distributor disc lll so that the latter is constrained to rotate with the shaft 3. Between the portion 4 of the shaft 3 and the disc lll are located a pair of spring members llflwhich urge the distributor disc lll upwardly so that its top, flat surface is pressed against a mating, downwardly directed iiat surface formed at the lower side of the housing portion 2.

The distributor means 1l is formed with an axial bore l5 which communicates with the pump chamber means 19 and which is of a smaller diameter at its end adjacent to the upper control surface of the disc 11 than at its lower portion which communicates with the chamber lll. Also, the `distributor disc ll is formed with a transverse bore 16 which extends across the axial bore 15. Communicating with the transverse bore lo are a bore 17 and a pair of bores 18 which extend between the transverse -bore 16 and the upper control surface of the disc 11. The pair of bores l are at the same radial distance from the bore `15.

The bores 2d of the housing 2 communicate through the bores 18 with the bore 16, and the number of bores 2t) is equal to the number of camming portions of the surface 8 of the cam ring 9, and the bores 2t? are unialiases formly distributed about the axis of the shaft 3 so that they are at equal angular distances from each other. The housing portion 2 is also formed with a number of passages 2l equal to the number of comming portions of the surface 8 yand also uniformly distributed about the axis of the shaft 3, and the bore 17 moves successively into communication with the several bores 2l during rotation of the shaft 3, only one of the bores 2l being shown in the drawing for the sake of clarity.

The housing portion 2 is also formed with a bore 22 which has its axis coinciding with the axis of the shaft 3, and the bore 22 communicates with the bore l5 as well as with a cylindrical chamber 23 which receives the solid portion 24 of a yieldable piston means 24, 25 of the invention. The portion 25 of the yieldable piston means 24, 2S is coaxial with and has a diameter larger than the portion 24 of the yieldable piston means, and the portion Z5 is separate from the portion 24 of the yieldable piston means and is formed with an axial bore 2o which passes through the yieldable piston portion 25. T he portion 25 of the yieldable piston means is received in the interior of a cylindricd body 27 which is guided for axial movement in a cylindrical bore formed in the housing portion 2. A pin 2f; extends into a slot which is formed in the exterior surface of the cylindrical body 27, and this pin ZS forms part of an adjusting means for adjusting the axial -position of the cylindrical body 27. The pin is ilixed eccentrically to a rotary adjusting shaft 2% sup- .ported for lturning movement about its axis in a bore of the housing portion 2, and extending to the exterior of the housing portion 2 where the shaft Z9 is iixcd to an adjusting lever 3G which may be manually turned or which may be turned by an unillustrated governor.

The interior 32 of the cylindrical body Z7, into which the portion Z5 of the yielda le piston means 24, 2S slidably extends, receives in its interior also a hollow pistou member 33 which has a sliding in the body 27 which is as Huid-tight as possible. Between the transverse top wall of the hollow piston 33 and the upper surface of the portion 25 of the yieldable piston means is a spring 3d which is compressed between the parts 33 and 25 and which urges the hollow piston 33 upwardly against a plug 3S which is threaded into the housing portion 2 and closes the bore of the latter which slidably receives the cylindrical body Z7.

At its exterior surface the cylindrical body 27 is formed with an axial groove 3o which extends 4throughout the entire length of the of the cylindrical body 27, and this groove 36 conunun-icates with a radial aperture 37 extending through the wall of the cylindrical body Z7. The groove 36 provides communication between the chambers 3S and 39 in the housing portion 2 which are respectively below and above the cylindrical body 27. The chamber 3S communicates with a bore til which in turn communicates with the inlet opening d2 through which fuel enters into the pump.

Each lof the :bores 2l forms part of a discharge passage 43 whose outer ond portion is enlarged and guides a valve member 4d held in the illustrated closed position by a spring 45 which urges the valve member ad against a valve seat formed by part of the housing pontion 2. The spring 45 rests against an inner shoulder formed in the discharge nipple t6 which is connected with a cond-uit 57 leading to the injection nozzle 48, and it is to be understood that there are as many passages d3, valves del, nipples 4-6, conduits 47, and nozzles d3 as there are cylinders for the internal combustion engine, and the several bores 2l respectively form parts of and communicate with the discharge passages 43.

The fuel is delivered from the tank 52 by a pump Si along the pressure conduit 53 to the inlet l2 of the pump housing portion 2, and a filter 5d is located in the fuel supply conduit 53. Excess fuel flows back to the tank 52 through a spring-pressed non-return valve 5o which communicates with the conduit 53s between the pump 5l l and the filter 5ft. Thus, excess fuel will automatically open the valve 5d to flow through the return conduit 55 bac-k to the tank 52.

The above-described pump operates as follows:

The pistons 5 iare shown in the drawing `at the end of their suction strokes. During the previous suction stroke the pump chamber lil land yall of the passages communieating therewith during the suction stroke were filled with fuel. During the continued turning of the shaft 3 beyond the position shown in the drawing the bores 2() are first closed -by the turning of the distributor lil to displace the openings i3 `beyond the bores Ztl. Tfhe the pressure strokes of the pistons 5 begin. During the movement of the pistons 5 toward each other along their pressure strokes the distributor means lll pilaces the bore T17 in communication with one of the passages 2l, 43. However, :the fuel which is pressed out of the pump chamber means lo by the pump piston means 5 during the pressure stroke thereof initially moves through the bores l5' and 22 into the chamber 23 of the means which guides the yieldable piston means 24, 25, displacing the piston portion 24 Iout of the chamber Z3 and iadvancing the piston portion 2'5 further into the interior of the cylindrical body 2'7 in opposition to the spring The movement 'of the yieldable piston means 24, 25' away from the pump chamber moans lil during the pressure stroke of the pump piston means o" continues as long as the fuel in the interior 32 of the cylindrical body 27' can flow out through the aperture 37. This action continues until the yieldable piston means 24, 25 closes the aperture v37, tand then no more fuel can llow out of the interior 32 of the cylindrical body 27, so that the movement of the yieldable piston means 2e, 25 is arrested when the piston portion 25 closes the aperture 37. During the remainder of the pressure stroke of each of the pistons S the fuel which is pressed out of the pump chamber 10 necessarily llows through the bore 2l Land along the passage 43 to open the valve it so that the fuel will be delivered through the conduit 47 to the nozzle 48. Immediately after the end of the pressure stroke `of the pump piston means 5, the suction stroke begins so that the valve 4d closes, and thus the injection of fuel is terminated. During the suction stroke 'of the piston means 5 the inlet passages 2d are again `opened so that the fuel under pressure from the fuel supply pump 5l will llow into the pump chamber means 16.

During the suction stroke of the pump piston means 5, which the pump piston means 5 carries out under the influence of centrifugal force as well as under the influence of the fuel flowing into the chamber it), the yieldable piston means 24, 215 which had its portions 24 and 25 tightly engaging each `other during the pressure stroke has these portions become separated from each other so that the fuel can llow through the bore 26 into the chamber 32, and this operation during the suction stroke of the pistons S is yof particular advantage since the aperture 37 is initially closed. Then the spring 34 returns the yieldable piston means 24, 25 to the illustrated starting position.

The larger diameter of the portion 25 of the yieldable piston means with respect to the portion 2d thereof produces in the chamber 32, during the injection process, a pressure which does not rise as greatly as the pressure in the pump chamber lll.A

The turning of the lever 30 will regulate the axial position lof the cylindrical body 27. By adjusting the axial position `of the cylindrical body 27, the distance that the yieldable piston means 24, 25 must move before closing the aperture 37 is determined, and in this way the amount of fuel `delivered to the injection nozzle at each cycle of operations is controlled. In other words, the position of the aperture 37 with respect to the piston 25 will control that portion of each pressure stroke which is devoted to the delivery of fuel into the chamber 23, and therefore this iadjustment will regulate that portion of reach pressure stroke which is devoted to delivery of fuel to the cylinders of the engine. [The pistons 5 always move through the same stnokes and thus will always displace lthe same amount of fuel, so that the more fuel which can be delivered to the chamber 23 the less will go to the engines and thus positioning of the cylindrical body 27 will adjust the amount of fuel which is delivered to the engine.

It should be noted that with the structure of Ithe invention there is no problem of maintaining a seal with the structune which adjusts the position of the cylindrical body 27, land furthermore the pontion 25 of the yieldable piston means has an exterior smooth cylindrical surface which -is guided about its entire circumference by the inner surface of the cylindrical body 27. This is in sharp contrast with a structure where, lfor example, the adjusting piston is provided with an inclined shoulder which controls an apenture such las the aperture 37. With such construction the angular position of the piston must be adjusted to adjust the moment when the inclined or helical shoulder covers or uncovers the aperture, and in addition the parts cooperate with each other frictionally in a manner which does not promote the best possible operation of the pump structure. All of these difficulties are avoided with the structure of the invention where the adjustment o-f the amount of fuel delivered to the engine is brought about by simply changing the axial position of the cylindrical body 27.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of pumps differing from the types described above.

While the invention has been illustrated and described as embodied in injection pumps, it is not intended to be limited to the details shown, since Various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

-Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior ant, fairly constitute essential characteristics of the generic or specific laspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a fuel injection pump, in combination, pump chamber means; pump piston means received in said pump chamber means and reciprocating therein along pressure and suction strokes during operation of the injection pump; yieldable piston means; means guiding said yieldable piston means for axial movement and placing the latter in communication with said pump chamber means for yielding axially when the pressure of fuel in said pump chamber means increases during pressure strokes of said pump piston means; a cylindrical body in which part of said yieldable piston means moves axially, said body being filled with fuel and formed with an aperture through which fuel discharges from the interior of said cylindrical body during movement of said yieldable piston means into said cylindrical body when said yieldable piston means yields during an increase in the pressure of the fuel in said pump chamber means, said yieldable piston means yielding until it closes said aperture in said cylindrical body; conduit means communicating with said pump chamber means and leading therefrom to an internal combustion engine for receiving fuel from said pump chamber means during pressure strokes of said pump piston means only after said aperture has been closed by said yieldable piston means; and adjusting means operatively connected to said cylindrical body for adjusting the latter axially with respect to said yieldable piston means so as to adjust the distance through which said yieldable piston means moves before closing said aperture, whereby the amount of fuel delivered to the engine during the pressure strokes of the pump piston means is adjusted.

2. In a fuel injection pump, in combination, pump chamber means; pump piston means received in said pump chamber means and reciprocating therein along pressure and suction strokes during operation of the injection pump; yieldable piston means; means guiding said yieldable piston means for axial movement and placing the latter in communication with said pump chamber means for yielding axially when the pressure of fuel in said pump chamber means increases during pressure strokes of said pump piston means; a cylindrical body in which part of said yieldable piston means moves axially, said body being filled with fuel and formed with an aperture through which fuel discharges from the interior of said cylindrical body during movement of said yieldable piston means into said cylindrical body when said yieldable piston means yields during an increase in the pressure of the fuel in said pump chamber means, said yieldable piston means yielding until it closes said aperture in said cylindrical body; conduit means communicating with said pump chamber means and leading therefrom to an internal combustion engine for receiving fuel from said said pump chamber means during pressure strokes of said pump piston means only after said aperture has been closed by said yieldable piston means, the portion of said yieldable piston means which is received in said cylindrical body being of a greater diameter than the portion thereof which communicates with said pump chamber means; and adjusting means operatively connected to said cylindrical body for adjusting the latter axially with respect to said yieldable piston means so as to adjust the distance through which said yieldable piston means moves before closing said aperture, whereby the amount of fuel delivered to the engine during the pressure strokes of the pump piston means is adjusted.

3. In a fuel injection pump, in combination, pump chamber means; pump piston means received in said pump chamber means and reciprocating therein along pressure and suction strokes during operation of the injection pump; yieldable piston means; means guiding said yieldable piston means for axial movement and placing the latter in communication with said pump chamber means for yielding axially when the pressure of fuel in said pump chamber means increases during pressure strokes of said pump piston means; a cylindrical body in which part of said yieldable piston means moves axially, said body being filled with fuel and formed with an aperture through which fuel discharges from the interior of said cylindrical body during movement of said yieldable piston means into said cylindrical body when said yieldable piston means yields during an increase in the pressure of the fuel in said pump chamber means, said yieldable piston means yielding until it closes said aperture in said cylindrical body; conduit means communicating with said pump chamber means and leading therefrom to an internal combustion engine for receiving fuel from said pump chamber means during pressure strokes of said pump piston means only after said aperture has been closed by said yieldable piston means, the portion of said yieldable piston means which is received in said cylindrical body being of a greater diameter than the portion thereof which communicates with said pump chamber means and said portions of said yieldable piston means being separate from each other, said portion of larger diameter being formed with an axial bore extending therethrough; and adjusting means operatively connected to said cylindrical body for adjusting the latter axially with respect to said yieldable piston means so as to adjust the distance through which said yieldable piston means moves before closing said aperture, whereby the amount of fuel delivered to the engine during the pressure strokes of the pump piston means is adjusted.

4. in an inection pump, in combination, rotary drive means lformed with a pair of diametrically opposed coaxial cylinders extending radially with respect to the axis of said rotary drive means and said rotary `drive means havl between said cylinders a pumping chamber; pair of pump piston means adapted to reciprocate axially in said cyiinders radially with respect to said drive means along pressure and suction strokes, said pump pistons moving toward each other and toward the axis of said drive means during their pressure strokes and away from each other and said axis during their suction strokes; yieldabie piston means coaxial with said drive means; .means guiding said yieldable piston means for axial `movement and piacing the latter in communication with said pump chamber so that said yieldable piston means will `move away from said pump chamber during the pressure strokes GI said pair of pump piston means; a cylindrical body coaxial with and slidably receiving said yieildable piston means, the iatter moving urther into said cylindrical body during the pressure strokes of said pair oi pump piston means, and said cylindrical body being formed with an aperture which is closed by said yieldable piston means after the latter has moved to a given extent into said cylindricalr body; conduit means communicating with said pump chamber `for directing fuel therefrom to an internal cornbustion engine after said aperture has been closed by said yieldable piston means; and adjusting means operatively connected to said cylindrical body for axiaiiy adjusting the same so as to reguiate the distance through which said yieldabie piston means before closing said aperture, whereby the amount ot fuel deiivered through said conduit means to the engine during the pressure strokes of said pair of pump piston `means can be adjusted.

5. in an injection pump as recited in claim 4, said yieldable piston means having a pair of portions respectively communicating with the interior of said cylindrical body and with said pump chamber, and the portion thereof which communicates With tle interior of said cylindrical body being of a larger diameter than the portion thereof which communicates with said lpump chamber.

6. in an injection pump as recited in claim 5, said portion of said yieidabie piston means which is oi larger diameter being separate from the portion thereof which is of smaller diameter and being formed with an axial bore extending therethrough.

Q 7. ln an injection pump as recited in claim 6, sprlng means urging said portions of said yieidable piston means toward each other. l

8. in an ing'ection pump, in combination, housing means formed with intake and discharge passages; rotary drive `means supported for rotary movement by said housing means and formed with a pair of coaxial diametrically opposed cylinders Whose common axis extends radially with respect to the axis of rotation of said rotary drive means; a pair of pump piston means reciprocating during operation of the injection pump in said cylinders, respectively, the space between said pair of pump piston means being a pumping chamber 'from which fuel is pumped during the pressure strokes of said pair of pump piston means and into which fuel flows during the suction strokes thereof; distributor means operatively connected to said drive means for rotary movement therewith and cooperating with said inlet and `discliarge passages for placing said intake pasages in communication with said pump chamber during the suction strokes of said pair `or piston means and said discharge passages in communication with said pump chamber during the pressure strokes of said pair of piston means; yieidable piston means placed by said `distributor means in continuous cotnn'iunication with the pumping chamber; means guiding said yieldable piston means for movement away from said pump chamber during the pressure strokes of said pair of piston means; a cylindrical body receiving a portion of said yieldable piston means and formed with an Aaperture through which uei discharges out of said cylindrical body during movement of said yieldable piston means further into the same during the pressure strokes of said pair of pump piston means, said yieldable piston means closing said aperture and said distributor means maintaining the discharge passages in communication with the pump chamber to receive uel therefrom during the pressure strokes of said pair of pump piston means after said aperture is closed by said yieldable piston means; and adjusting means loperatively connected to said cylindrical `body for axially adjusting the same to regulate the distance through which said yieldable piston means vmoves before closing said aperture, whereby the amount of fuel delivered to the discharge passages can be regulated.

No references cited. 

1. IN A FUEL INJECTION PUMP, IN COMBINATION, PUMP CHAMBER MEANS; PUMP PISTON MEANS RECEIVED IN SAID PUMP CHAMBER MEANS AND RECIPROCATING THEREIN ALONG PRESSURE AND SUCTION STROKES DURING OPERATION OF THE INJECTION PUMP; YIELDABLE PISTON MEANS; MEANS GUIDING SAID YIELDABLE PISTON MEANS FOR AXIAL MOVEMENT AND PLACING THE LATTER IN COMMUNICATION WITH SAID PUMP CHAMBER MEANS FOR YIELDING AXIALLY WHEN THE PRESSURE OF FUEL IN SAID PUMP CHAMBER MEANS INCREASES DURING PRESSURE STROKES OF SAID PUMP PISTON MEANS; A CYLINDRICAL BODY IN WHICH PART OF SAID YIELDABLE PISTON MEANS MOVES AXIALLY, SAID BODY BEING FILLED WITH FUEL AND FORMED WITH AN APERTURE THROUGH WHICH FUEL DISCHARGES FROM THE INTERIOR OF SAID CYLINDRICAL BODY DURING MOVEMENT OF SAID YIELDABLE PISTON MEANS INTO SAID CYLINDRICAL BODY WHEN SAID YIELDABLE PISTON MEANS YIELDS DURING AN INCREASE IN THE PRESSURE OF THE FUEL IN SAID PUMP CHAMBER MEANS, SAID YIELDABLE PISTON MEANS YIELDING UNTIL IT CLOSES SAID APERTURE IN SAID CYLINDRICAL BODY; CONDUIT MEANS COMMUNICATING WITH SAID PUMP CHAMBER MEANS AND LEADING THEREFROM TO AN INTERNAL COMBUSTION ENGINE FOR RECEIVING FUEL FROM SAID PUMP CHAMBER MEANS DURING PRESSURE STROKES OF SAID PUMP PISTON MEANS ONLY AFTER SAID APERTURE HAS BEEN CLOSED BY SAID YIELDABLE PISTON MEANS; AND ADJUSTING MEANS OPERATIVELY CONNECTED TO SAID CYLINDRICAL BODY FOR ADJUSTING THE LATTER AXIALLY WITH RESPECT TO SAID YIELDABLE PISTON MEANS SO AS TO ADJUST THE DISTANCE THROUGH WHICH SAID YIELDABLE PISTON MEANS MOVES BEFORE CLOSING SAID APERTURE, WHEREBY THE AMOUNT OF FUEL DELIVERED TO THE ENGINE DURING THE PRESSURE STROKES OF THE PUMP PISTON MEANS IS ADJUSTED. 